Identifying Clues to Parkinsons Disease

November 12, 2012

Two new hereditary variants have been identified for Parkinsons disease, say researchers, and also the role genetics play in this neurodegenerative disorder. Although the causes of Parkinsons disease remain unknown, environmental and genetic factors are influences. Genetics play a role in a small percentage of cases which affect people who are under the age of 50. This is known as early-onset Parkinsons. The part genes play in late-onset Parkinsons is not as well known.

In a new study, published in the journal PLoS Genetics, Nicholas Eriksson, PhD, of the California based 23andMe gene testing company which targets direct to consumer testing, says, “About a dozen genetic associations with Parkinsons have been confirmed, and many more remain to be discovered. Each new generic variant we find gets us a little closer to being able to see the full picture of how genes impact this disease. Roughly 10 genetic variants that contribute to Parkinsons had been found and we added another two to the list”. It is estimated that about 25% of the gene variation in susceptibility to developing Parkinsons disease is because of genetic factors according to Eriksson and colleagues. They also estimate that about a quarter of the variation in susceptibility to the disease is due to genetic factors.

SCARB2 has been recognized as one of the newly identified genetic variants with a known Parkinsons disease pathway relating to protein degradation.

The other newly identified variant is called SREBF1, and it is not connected with any known Parkinsons pathway. Do says, “This variant is involved in lipid metabolism. Its association with Parkinsons is not really clear, which is what makes it exciting because it highlights a new area to look at”.

The researchers have estimated that only about 7% of the genetic variants related to Parkinsons disease have been identified highlighting the need for more work to identify the remaining 93%.

Erikssons colleague Chuong B Do, PhD says “While the genetic variants, or mutations, identified to date explain only a small percentage of Parkinsons cases, the gene studies have provided clinically relevant information.” He points out that, “One identified mutation is associated with a 50% lifetime risk for developing the disease. This one variant accounts for a very small percentage of the total disease burden, but for people who do have the variant it is quite significant.” he says.

A genome-wide study was carried out by Chuong B Do, PhD and fellow researchers. Involved in this study were 3,400 Parkinsons patients and almost 30,000 people without the disease who were 23andMe clients. This study took place in an effort to understand genetic influences in both early and late-onset Parkinsons. Recruitment of the Parkinsons patients was aided with the assistance of the Michael J Fox Foundation, the Parkinsons Institute and the National Parkinsons Foundation. The genetic testing company 23andMe funded this study solely.

The completion of the Human Genome Project allowed the study of genome wide association using the following tools: Computerized human genome sequence database, human genetic variation mapping and also the constantly developing technologies which make it easier to analyze the genetic variations related to Parkinsons disease.